Tides at the new ferry terminal on Merseyside have forced the Steam Packet Company to change its winter sailings schedule.
The company says trials with the Manxman and Ben My Chree found problems safely mooring them at various tidal heights.
It says while it's working to solve the problems, it's changing Liverpool sailing times from early November until the end of December.
In a statement, the company says it's contacting passengers about the changes.